Why emails are not received in Salesforce lightning experience?

I am writting a trigger on contact to send an email alert when a file is uploaded in notes and attachment. The email is sent when I am attaching file in Notes and attachment related list of contact in classic but when I am attaching the file in Notes and attachments of Contact in lightning experience than i am not receiving an email.What is the reason behind this?

• This discussion was modified 6 years, 5 months ago by  Prachi.
• This discussion was modified 6 years, 5 months ago by  Forcetalks.
• This discussion was modified 6 years, 5 months ago by  Forcetalks.